New evidence out of Washington State shows cannabis reform is having exactly that effect. Low-level marijuana prosecutions for adults over 21 have dropped by 98 percent since voters legalized the drug, according to state statistics analyzed by the American Civil Liberties Union.

There were just 120 prosecutions in the state for misdemeanor marijuana possession in 2013. That’s just 2 percent of the 5,500 cases tried the year before.

Voters in Washington approved Initiative 502, which legalized recreational weed for adults over 21, in November 2012. Colorado voters took the same step in that election. The first retail pot shops opened there Jan. 1; stores are scheduled to open in Washington in the summer.

“The data strongly suggest that I-502 has achieved one of its primary goals – to free up limited police and prosecutorial resources,” said Mark Cooke, criminal justice policy counsel for the ACLU of Washington. “These resources can now be used for other important public safety concerns.”

Marijuana prosecutions were already declining in Washington before legalization took effect, with a 30 percent drop between 2009 and 2012. Possession cases against users under 21 continued to decrease slowly after legalization, indicating other forces are contributing to the overall decline.

At the same time, court filings for other cannabis crimes – felony charges such as growing or selling without a license, for example – have stayed relatively constant, according to the ACLU.

Not all the news is good, however. The civil liberties group reports that racial bias is still prevalent in arrest and prosecution patterns. A black adult is still three times more likely to be charged with a low-level marijuana offense than is a white adult.

The drop in cases has affected some parts of the state more than others. In King County, home of Seattle, prosecutors said they have not seen a significant change in their workload. That, said Ian Goodhew, deputy chief of staff at the county prosecutor’s office, is because that office didn’t handle many possession cases to begin with.

“There’s no great relief of workload,” Goodhew said. “All this has meant is maybe our calendar in District Court in the Seattle division is maybe, instead of 46 cases in a day, 44 or 43 or 42. We’re no longer filing misdemeanor marijuana cases, but we were not expending any significant resources on those cases at the time I-502 passed.”

Based in California, Ben writes about marijuana culture, cultivation and edibles. He's a regular contributor at marijuanamarketplace.com, themarijuanachef.com, marijuanagrowhelp.com, and stonerthings.com